The present invention relates generally to spectacle frames and deals more particularly with supporting and positioning plates suitable for the controlled positioning of a spectacle frame on an apparatus of any kind.
The controlled positioning of a spectacle frame may be necessary for example on a copying machine suitable for cutting a pattern or an ophthalmic lens under the control of a sensor sensitive to the contour of the rim of a spectacle frame.
In order to ensure that a pattern of this kind, and therefore the ophthalmic lens the cutting of which it will subsequently permit, is correctly centred in relation to the spectacle frame rim for which it is intended, it is necessary that the position of this spectacle frame on the corresponding copying machine should be adjusted accordingly, and the same is true in cases where a copying machine is able to effect the direct cutting of an ophthalmic lens with the aid of the spectacle frame in question, without utilising a pattern.
It is for this reason that it is customary to position a spectacle frame on a machine of this kind with the aid of a supporting and positioning plate adapted to permit the control of this positioning.
In supporting and positioning plates intended for this purpose which are known at the present time, the fastening means used for holding a spectacle frame are most usually simple support feet of the claw type which bear against the upper face of the spectacle frame placed against the corresponding supporting and positioning plate and in practice are not able to prevent accidental lateral displacement of the spectacle frame parallel to the plate; plates of this kind are displaced parallel to their plane in relation to a support table and then locked on the latter in the position corresponding to the desired adjustment for the spectacle frame in question.
Consequently this adjustment cannot be effected with great accuracy, while in addition the adjustment is relatively delicate to make.
The present invention on the other hand has as its object a supporting and positioning plate for spectacle frames which is adapted to effect the fastening and positioning of a spectacle frame easily, rapidly, accurately, and securely.